Newt Gingrich officially suspended his GOP presidential campaign Wednesday – though it was more like another episode in the long goodbye that started weeks ago.

“It has been an amazing year for me and Callista,” Gingrich, the former House speaker, said at a Hilton Hotel in northern Virginia. "Today, I am suspending the campaign, but suspending the campaign does not mean suspending citizenship. Callista and I are committed to be active citizens. We owe it to America."

Delivering a roughly 20-minute address, Gingrich vowed to, with his wife, remain “active citizens,” as he looked back on the primary campaign and looked ahead to what challenges remain in America.

But he also declined to endorse Mitt Romney for the GOP nomination -- meaning another announcement could still be on the way and potentially giving Gingrich another chance to deliver one of the extended monologues he is known for.

Even so, Gingrich has slowly slipped away from the limelight in the Republican race.

The campaign suggested in March that Gingrich might quit should he fail to win Mississippi or Alabama, but the campaign limped on. Aides then revealed last week that the candidate would be calling it quits – but pushed off the day of the announcement itself until Tuesday, then delayed that announcement until Wednesday afternoon.

Despite not endorsing Romney, Gingrich did make clear that his doubts during the primary campaign about Romney’s conservatism are dwarfed by his concerns about President Obama winning another term.

“This is not a choice between Mitt Romney and Ronald Reagan – this is a choice between Mitt Romney and the most radical leftist president in American history,” Gingrich said.

Gingrich’s candidacy had seen its fair share of twists and turns since its launch last summer. He got off to a rough start -- losing his staff and finishing fourth in the Iowa caucuses, which kicked off the 2012 primary season -- but later gained momentum with a big win Jan. 21 in South Carolina.

He scored a must-win primary victory March 6 in Georgia, the state he represented in Congress for 20 years. But his plans of becoming the conservative alternative to frontrunner Romney -- and to Romney's deep-pocketed and well organized campaign -- during primaries across the South unraveled when Rick Santorum pulled off a string of wins in the region.

The wins moved Santorum, a former U.S. senator from Pennsylvania, into position as Romney’s closest competitor in the race to face Obama in November. But like Santorum, who suspended his campaign in last month, Gingrich also had trouble raising money to stay in the race. His campaign is nearly $4 million in debt.

Santorum also has not officially endorsed Romney, the likely GOP nominee who remains in the race with Texas Rep. Ron Paul.

"I want to thank the former speaker for echoing my calls for monetary policy reform including a full audit of the Federal Reserve, steps that will bring America closer to lasting economic prosperity for middle-class Americans who bear the brunt of the dangerous and unjust inflation tax," Paul said.

Gingrich, a skilled debater, stayed true Wednesday to his penchant for lofty ideals and ideas, predicting his grandchildren Maggie and Robert, who stood beside him on stage, would live in world with frequent space travel, a cure for Alzheimer’s disease and autism and advances in mental health care.

“I’m not certain I’ll get to the moon, but Maggie and Robert will,” he said.

Gingrich acknowledged that his pitch for a moon colony – delivered to voters in Florida’s beleaguered Space Coast – was “not my most clever idea,” or at least according to Callista.

In 1994, Gingrich helped Republicans retake the House after 40 years. But he has since been criticized, including this year, by some of those House Republicans for lacking leadership skills.

The Obama re-election campaign released a web video Wednesday that included clips for the primaries in which Gingrich criticized Romney on issues from immigration to Romney's career as a venture capitalist.